This re-lands #41417 with a slight change that will hopefully not tickle the analyzer as it did before. The last time I tried to land this, the analyzer succeeded for the analyze step in Cirrus, and locally, but failed in an integration test.

* remove splash logic

* update tests

This adds a description of the command needed to run the driver test

This reverts the engine to a previous hash because of #41484

ReorderableListView was constructing a GlobalObjectKey using
the child key as the value. This only had the intended behavior
if the child key was identical across build method invocations.

The new strategy is to scope the child key's value to the
State object's identity, allowing child keys to have value
compare semantics while disambiguating among different list view
instances.

git@github.com:flutter/engine.git/compare/18bc0b259641...e31b2ff64dc2

git log 18bc0b259641..e31b2ff64dc2 --no-merges --oneline
2019-09-27 bkonyi@google.com Roll src/third_party/dart 403c4af720..7901c508c8 (7 commits)


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git@github.com:flutter/engine.git/compare/a206557f8fb8...18bc0b259641

git log a206557f8fb8..18bc0b259641 --no-merges --oneline
2019-09-27 skia-flutter-autoroll@skia.org Roll src/third_party/skia b83cc76a5e3a..296743a86281 (1 commits) (flutter/engine#12491)
2019-09-27 bkonyi@google.com Roll src/third_party/dart 327bc451f8..403c4af720 (9 commits)
2019-09-27 skia-flutter-autoroll@skia.org Roll fuchsia/clang/mac-amd64 from HfPKR... to zpVtV... (flutter/engine#12473)


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This reverts commit eb3e2f55 because of a suspected analyzer bug.  Reverting to investigate.

git@github.com:flutter/engine.git/compare/ce6ab8ce25fa...a206557f8fb8

git log ce6ab8ce25fa..a206557f8fb8 --no-merges --oneline
2019-09-27 skia-flutter-autoroll@skia.org Roll src/third_party/skia ec85f407bfee..b83cc76a5e3a (15 commits) (flutter/engine#12472)
2019-09-27 30870216+gaaclarke@users.noreply.github.com Added a default entrypoint variable to match android syntax. (flutter/engine#12370)
2019-09-26 tauu@h2overclock.de [web_ui] add missing dispose handler for MethodCalls to flutter/platform_view (flutter/engine#12226)
2019-09-26 tauu@h2overclock.de [web_ui] PersistedPlatformView attribute update handling to enable resizing (flutter/engine#12227)
2019-09-26 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/mac-amd64 from z3PaM... to HoRV8... (flutter/engine#12471)


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This addresses comments in the original PR (#41245) that introduced Intent.doNothing, adds tests, and fixes an issue with it.

git@github.com:flutter/engine.git/compare/5b952f286fc0...ce6ab8ce25fa

git log 5b952f286fc0..ce6ab8ce25fa --no-merges --oneline
2019-09-26 bkonyi@google.com Roll src/third_party/dart 6ff8d2199d..327bc451f8 (12 commits)


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add tests to ensure the sdk is well-formed

This reverts commit e47a1dc2.

git@github.com:flutter/engine.git/compare/0018135a1c28...5b952f286fc0

git log 0018135a1c28..5b952f286fc0 --no-merges --oneline
2019-09-26 matthew-carroll@users.noreply.github.com Forwards Flutter View to platform views and detaches when needed. (flutter/engine#12359)
2019-09-26 50856934+nturgut@users.noreply.github.com Reflect selection changes in Firefox for text editing (flutter/engine#12447)
2019-09-26 franciscojma86@gmail.com Adds support for 5 mouse buttons (flutter/engine#12450)


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Fixed check for path equality.  It was too strict, disallowing leading "./".

git@github.com:flutter/engine.git/compare/5b5fd7508c63...0018135a1c28

git log 5b5fd7508c63..0018135a1c28 --no-merges --oneline
2019-09-26 garyq@google.com Make kDoNotResizeDimension public so framework can use it directly (flutter/engine#12448)
2019-09-26 skia-flutter-autoroll@skia.org Roll src/third_party/skia 559ffe4a23ce..ec85f407bfee (44 commits) (flutter/engine#12463)
2019-09-26 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/linux-amd64 from PyQPO... to YDv3O... (flutter/engine#12462)


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git@github.com:flutter/engine.git/compare/b126ba758533...5b5fd7508c63

git log b126ba758533..5b5fd7508c63 --no-merges --oneline
2019-09-26 chinmaygarde@google.com Revert "Support accessibility labels on iOS switches. (#12404)" (flutter/engine#12466)
2019-09-26 1036976+brandondiamond@users.noreply.github.com Support accessibility labels on iOS switches. (flutter/engine#12404)


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This changes the way ActionDispatchers are found by the Actions widget, so that by default it will look for dispatchers of the parent Actions widgets instead of just creating a default ActionDispatcher. This allows overriding of the ActionDispatcher at the top level: before, the custom action dispatcher would only be invoked if explicitly set on all the Actions widgets.

This is not a breaking change because there was a default value to the dispatcher parameter before that performed this function, and not specifying the dispatcher anywhere will still result in a default dispatcher being created.

The proposed change will change focus handling when pushing and popping routes so that the FocusScopeNode for the route receives focus when pushed, and that the FocusScopeNode in the navigator receives focus when the route is popped.

This means that the last setFirstFocus call on the scope is used to determine which control actually receives focus. When the focus scope receives focus, it traverses its children, trying to find a non-scope node that is the "first focus" of itself or a child node.

This is a breaking change, because the focus behavior has changed. If you push a route after this change, and had a 'first focus' set on a widget via FocusScopeNode.setFirstFocus, it won't currently receive focus immediately, but after this change it will. Similarly, if you pop a route after this change, the focus will go back to where it was before the route was pushed, which is correct, but different from what happens now.

Adds very preliminary support for Windows and Linux plugins:
- Adds those platforms to the new plugin schema, initially supporting just a plugin class.
- Adds C++ plugin registrant generation for any Windows or Linux plugins found.

This doesn't have yet have any build tooling for either platform, so anyone using the generated registrant still needs to do manual build configuration. This reduces the manual work, however, and creates a starting point for future tooling work.

As with all Windows and Linux work at this time, this is not final, and subject to change without warning in the future (e.g., Windows could potentially switch to a C# interface, or
'linux' may change to 'gtk' or 'linux_gtk' in pubspec.yaml).

git@github.com:flutter/engine.git/compare/b520d7fd4b6d...b126ba758533

git log b520d7fd4b6d..b126ba758533 --no-merges --oneline
2019-09-26 liyuqian@google.com Add .mskp file to binary format (flutter/engine#12454)


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* MouseRegion documentation claimed that onEnter and onExit
  would track entry and exit regardless of whether the pointer was
  down or up
* It did such, but when grabbing the value of `event.down` from
  the passed event, the value was always `false`
* PointerEnterEvent and PointerExitEvent were overriding the value
  passed from PointerEvent in constructors, even if the value was true
  e.g. in invocations of .fromMouseEvent((PointerMoveEvent...))
* This change now passes the value along to PointerEnter/ExitEvents
  while providing it a default of false, and updates documentation

Fixes #40637